Method for marking golf ball and golf ball

ABSTRACT

The invention provides a golf ball marking method of marking the surface of a golf ball with a character, pattern or the like by a direct or indirect printing technique, comprising applying a marking layer onto the ball surface for marking, the marking layer being of a two-layer structure consisting of a lower layer of a composition containing a color pigment in a lower layer ink medium and an upper layer which is formed on the lower layer from a composition containing a metal powder in an upper layer ink medium and which is transparent or translucent and has brilliance, and adjusting the content of the metal powder and the thickness of the upper layer such that the relation of the content (wt %) of the metal powder relative to the upper layer ink medium solids to the thickness (μm) of the upper layer may satisfy the inequality: 1≦[metal powder content (wt %)]×[upper layer thickness (μm)]≦10. When it is desired to impart brilliance in a dark color such as black, the dark color is improved in sharpness and reproducibility.

BACKGROUND OF THE INVENTION

This invention relates to a golf ball marking method for marking thesurface of a golf ball with a character, pattern or the like and a golfball resulting from the method. More particularly, it relates to a golfball marking method in which even when it is desired to impartbrilliance in a dark color such as black, the dark color is improved insharpness and reproducibility, and a golf ball resulting from themethod.

In general, the surface of golf balls is marked with characters,numerals, and patterns such as trade names and logo marks by a direct orindirect printing technique. Such marks include those marks which serveto impart sharpness and an aesthetic look to the outer appearance ofballs when given brilliance. Proposed as means for providing brillianceis a technique of previously incorporating a metal powder such asaluminum or copper powder in ink and using the ink to apply metallictone marks to golf balls.

However, if it is desired to impart brilliance in a dark color such asblack to the golf ball surface, there is a tendency that the dark colorlacks sharpness and reproducibility.

Also, JP-A 11-114093 describes a golf ball on which marks are formedusing a transfer film having an ink layer containing a pigment and ametal powder. U.S. Pat. No. 6,558,277 discloses a golf ball having thecolor flop effect that the color sharply changes with the viewingdirection, and U.S. Pat. No. 5,427,378 discloses a golf ball having aresinous cover on a surface of which a plurality of light reflectiveparticles are dispersed.

These golf balls, however, have the problem that when it is desired toimpart brilliance in a dark color such as black, the dark color is stillinsufficient in sharpness and reproducibility.

SUMMARY OF THE INVENTION

An object of the present invention, which has been made under theabove-discussed circumstances, is to provide a golf ball marking methodin which when it is desired to impart brilliance in a dark color such asblack, the dark color is improved in sharpness and reproducibility, anda golf ball resulting from the method.

In an attempt to divide a marking layer to be applied to the golf ballsurface into two layers, use an ink layer for developing the desiredcolor as the lower layer, and use a transparent ink layer for impartingbrilliance as the upper layer so as to enhance the outer appearance ofthe ball and especially, impart brilliance in a dark color such asblack, the inventor made extensive investigations to improve thesharpness and reproducibility of the dark color. As a result, theinventor has discovered a golf ball marking method characterized in thatthe upper layer is a transparent or translucent layer which is formed ofa composition containing a metal powder, typically aluminum powder, inan ink medium and is endowed with brilliance, and that the content ofthe metal powder and the thickness of the upper layer are adjusted suchthat the relation of the content (wt %) of the metal powder relative tothe solids of the upper layer ink medium to the thickness (μm) of theupper layer may satisfy the inequality: 1≦[metal powder content (wt%)]x[upper layer thickness (μm)]≦10.

Accordingly, the present invention provides a golf ball marking methodand a golf ball, which are defined below. [1] A golf ball marking methodof marking the surface of a golf ball with a character, pattern or thelike by a direct or indirect printing technique, characterized by thesteps of:

-   -   applying a marking layer onto the ball surface for marking, the        marking layer being of a two-layer structure consisting of a        lower layer of a composition containing a color pigment in a        lower layer ink medium and an upper layer which is formed on the        lower layer from a composition containing a metal powder in an        upper layer ink medium and which is transparent or translucent        and has brilliance, and adjusting the content of the metal        powder and the thickness of the upper layer such that the        relation of the content (wt %) of the metal powder relative to        the solids of the upper layer ink medium to the thickness (μm)        of the upper layer may satisfy the inequality: 1≦[metal powder        content (wt %)]×[upper layer thickness (μm)]≦10.

[2] The golf ball marking method of [1], wherein the character, patternor the like is marked by a pad printing technique.

[3] The golf ball marking method of [1], wherein the character, patternor the like is marked by thermal transfer using a transfer member.

[4] The golf ball marking method of [3], wherein a mode of printing thecharacter, pattern or the like on the transfer member is silk screenprinting.

[5] The golf ball marking method of [4], wherein the silk screenprinting uses a screen having a ruling of 200 to 300 lines.

[6] The golf ball marking method of [1], wherein the metal powder has anaverage particle size of up to 20 μm.

[7] The golf ball marking method of [1], wherein the metal powder is analuminum powder.

[8] The golf ball marking method of [3], wherein a mode of printing thecharacter, pattern or the like on the transfer member is gravureprinting.

[9] A golf ball characterized in that a marking layer is formed on thegolf ball surface by the method of any one of [1] to [8].

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a gold ball marking method according to oneembodiment of the invention.

FIG. 2 is a plan view showing a ball surface portion where a mark isapplied.

DETAILED DESCRIPTION OF THE INVENTION

The golf ball marking method of the invention intends to enhance theouter appearance of marking by dividing a marking layer that representsa character, pattern or the like on the golf ball surface into upper andlower layers.

The marking layer is of a two-layer structure consisting of a lowerlayer of a composition containing a color pigment in a lower layer inkmedium and an upper layer which is formed on the lower layer from acomposition containing a metal powder in an upper layer ink medium forimparting brilliance and which is transparent or translucent.

The upper layer or lower layer ink medium is an intermediate which isavailable in the process of preparing printing ink and has a fullprinting function as ink once it is colored. The ink medium is generallycomposed of an ink resin, a plasticizer, fillers (such as extenderpigments and fillers), a solvent and the like.

The ink media for the upper and lower layers may be the same ordifferent although identical media are desired for the adhesion betweenlayers.

The ink resins which can be used herein include vinyl chloride-vinylacetate copolymers, vinyl chloride-vinyl acetate-vinyl alcoholcopolymers, urethane resins, polyester resins, polyethylene imineresins, polyamide resins, acrylic resins, chlorinated polyolefin resins,and nitrocellulose. It is preferred that the ink resins be colorless andtransparent because they do not reduce the color effect that developswhen a pigment is admixed.

The plasticizers which can be used herein include dibutyl phthalate,dioctyl phthalate, dioctyl adipate, dioctyl azelate, triethyl citrate,tributyl acetylcitrate, dibutyl sebacate, and dioctyl sebacate.

The extender pigments which can be used herein include calciumcarbonate, titanium oxide, barium sulfate, alumina white, zinc oxide,clay and powdered silica.

In the invention, from the standpoint of imparting brilliance, a metalpowder is incorporated in the ink medium. The preferred form of metalpowder is a metal paste having metal powder dispersed in a solvent. Themetal powder preferably has an average particle size of up to 20 μm,more preferably up to 15 μm. An average particle size larger than therange is inconvenient in that the image quality must be accordinglyreduced.

As to the type of metal powder, use may be made of aluminum, chromium,cobalt, steel, silver, gold, copper, nickel and various alloys of any ofthe foregoing metals. Of these, use of aluminum is preferred.

The color pigment which can be used in the lower layer in the inventivemethod may be selected from materials well known as pigments havingchromatic colors. Such pigments may be either organic or inorganic.Examples include carbon black, graphite, black iron, red lead, red ironoxide, ultramarine, Prussian blue, Lithol Red B, Brilliant Scarlet G,Pigment Scarlet 3B, Brilliant Carmine 6B, Lake Red C, Lake Red D,Permanent Red 4R, Bordeaux 5B, Bordeaux 10B, Para Red, Watchung Red,Benzidine Orange, BON Maroon L, BON Maroon M, Brilliant Scarlet,Vermilion Red, Phthalocyanine Blue, Phthalocyanine Green, Fast Sky Blue,Aniline Black, zinc white, white lead, zinc yellow, Dis-Azo Yellow,barium sulfate, Fast Yellow G, Fast Yellow 10G, etc., which may be usedalone or in admixture of two or more.

In the marking method of the invention, the effect of the inventionbecomes prominent when pigments of dark colors such as black are usedrather than pigments of light colors. Specifically, the effect of theinvention becomes prominent when pigments toned to an L value of up to60 as expressed by Munssel notation system (JIS Z8721) are used.

In the invention, the content of the metal powder and the thickness ofthe upper layer are adjusted such that the relation of the content (wt%) of the metal powder relative to the solids of the ink medium to thethickness (am) of the upper layer may satisfy the inequality: 1≦[metalpowder content (wt %)]×[upper layer thickness (μm)]≦10.

The above inequality has a technical significance of exerting insynergism the effect of imparting brilliance to the ball outerappearance and the effect of improving color reproducibility. In theabove inequality, the preferred upper limit is 9, and more preferably 6.The preferred lower limit is 2. If the value is less than 1, the effectof imparting brilliance to marking is not fully exerted. A value inexcess of 10 may allow the metal powder such as aluminum powder to exerta hiding effect so that the color of lower layer ink medium may becanceled by the color of metal.

The thickness of the upper layer is desirably adjusted to a range of 1to 12 μm. If the upper layer is thicker than the range, the markinglayer printed on the ball surface becomes thicker as a whole, which maydetract from ball functions such as impact durability.

The technique of marking the golf ball surface with characters, patternsor the like may be any of ordinary techniques commonly used in themarking of golf balls. For example, direct printing techniques based onpad printing, and indirect printing techniques such as a transfertechnique of using an all “solid” transfer film and imprinting with astamp, and a thermal transfer technique of printing through thermaltransfer. The type of marks, the marking position, the number of marksand the like are not particularly limited. Characters, numerals, andpatterns such as trade names and logo marks may be marked at any desiredposition on the golf ball surface.

For example, when a mark is printed on the golf ball surface using atransfer film, an ink composition which is previously prepared isprinted on a polypropylene film or biaxially oriented polypropylene filmor a laminate foil thereof with glassine paper, commonly used in theart, to form a transfer film. The technique of forming a marking layerrepresentative of a predetermined pattern on the base film is preferablyscreen printing or gravure printing. When screen printing is employed,it is desirable to use a screen having a ruling of 200 to 300 lines.

The mark can be transferred to a golf ball by laying the transfer inklayer on the position of the golf ball where the mark is to be formed,pressing from the base film side while heating at about 90-150° C. orabout 150-180° C., thereafter peeling the base film. It is noted that aclear coat may be applied onto the thus transferred mark, if desired.

The thickness of the marking layer used herein is desirably previouslyadjusted so that it may have a thickness of 2 to 16 μm, especially 4 to12 μm when transferred or otherwise applied onto the ball.

The golf balls used in the invention are not particularly limited withrespect to their structure, material, manufacturing process and thelike. The balls can be manufactured by using well-known materials andconventional molding. The ball structures may be either wound golf ballsor one- or two-piece solid golf balls or multi-piece solid golf ballshaving a cover of two or more layers.

EXAMPLE

Examples and Comparative Examples are given below for illustrating theinvention although the invention is not limited to these Examples.

In each of Examples 1 to 6 and Comparative Examples 1 to 9, a transferfilm 10 was prepared as shown in FIG. 1A, by using a biaxially orientedpolypropylene film 4 of 33 μm thick as a base film, laminating a markinglower layer 2 of a black ink composition of the formulation shown inTable 1 and a marking upper layer 3 of the formulation shown in Table 2in combination on the base film (transfer foil) 4 while utilizing a silkscreen printing or gravure printing technique.

Separately, two-piece balls comprising a core of crosslinked rubberbased on polybutadiene rubber which is enclosed with an ionomerresin-based cover material having a Shore D hardness of 65 to athickness of about 2 mm were furnished as the golf balls to which themark was to be transferred. It is noted that the balls on the surfacewere administered plasma surface treatment. As shown in FIG. 1B, usingthe transfer film 10 of the construction reported under Examples 1-6(Table 3) and Comparative Examples 1-9 (Tables 4 and 5), a generallycrisscross shaped mark 2 having length and width sizes of about 12 mmwas thermally transferred to the treated surface 1 of the golf ball. Themarked state is shown in FIG. 2. The transfer temperature was 140° C.and a silicone pad was pressed for one second. Example 7 used directprinting by a pad printing technique. Specifically, the lower layer inkmedium “a” was printed on the ball surface by the pad technique, and theupper layer ink medium “C” was printed thereon by the pad technique.

The ball thus marked by the method of each example was evaluated by thefollowing tests.

Brilliance

In an outdoor environment under sunlight, the marked portion wasvisually observed.

-   -   ⊚: full metallic luster by light reflection    -   ◯: metallic luster by light reflection    -   Δ: insufficient light reflection, insufficient metallic luster    -   X: little or no light reflection, no luster        Reproduction of Lower Layer Color

In a room under white illumination, the marked portion was visuallyobserved.

-   -   ⊚: lower layer color is reproduced intact    -   ◯: lower layer color is almost reproduced    -   Δ: some mixing of upper layer color with lower layer color        (white looking)    -   X: different color from lower layer color        (metal color develops predominantly)        Abrasion Test

A porcelain ball mill was charged with balls together with the sand usedin the bunker in a golf course and operated for 2 hours. Thereafter, theballs were taken out, and the marked portions were visually inspectedfor peel and damage according to the following criterion.

-   -   ⊚: no peel or damage    -   ◯: no peel or damage over an extent of at least 90% of the        marked portion    -   Δ: no peel or damage over an extent of at least 70% of the        marked portion    -   X: peeled or damaged over an extent of at least 30% of the        marked portion        Impact Durability

Using a driver (W#1) at a head speed of 45 m/s, the golf ball marked ineach example was hit toward a fabric target, which was repeated 200times. The degree of damage on the marked portion was visually ratedaccording to the following criterion.

-   -   ⊚: no peel or damage    -   ◯: no peel or damage over an extent of at least 90% of the        marked portion    -   Δ: no peel or damage over an extent of at least 70% of the        marked portion

X: peeled or damaged over an extent of at least 30% of the markedportion TABLE 1 Parts by weight a b c d e f Ink Sol- Resin 1 18 18 18 1818 18 medium ids Resin 2 2 2 2 2 2 2 Plasticizer 15 15 15 15 15 15Extender 15 15 15 15 15 15 pigment Sol- Cyclohexane 25 25 25 25 25 25vent High-boiling 25 25 25 25 25 25 solvent Total 100 100 100 100 100100 Color Carbon black 5 4 3 2 1 pigment Aluminum paste 8 16 24 32 40

TABLE 2 Parts by weight A B C D E F G Ink Sol- Resin 1 18 18 18 18 18 1818 medium ids Resin 2 2 2 2 2 2 2 2 Plasticizer 15 15 15 15 15 15 15Extender 15 15 15 15 15 15 15 pigment Sol- Cyclohexane 25 25 25 25 25 2525 vent High-boiling 25 25 25 25 25 25 25 solvent Total 100 100 100 100100 100 100 Color Aluminum paste 0.1 0.3 0.5 0.8 1.0 1.5 2.0 pigmentAluminum content 0.14 0.41 0.69 1.10 1.38 2.07 2.76 (% based on solids)Resin 1: vinyl chloride-vinyl acetate-vinyl alcohol copolymer resin (DowChemical, UCAR VAGH)Resin 2: epoxy-containing acrylic polymer (NOF Corp., Blenmer CP-30)Plasticizer: dibutyl phthalateExtender pigment: calcium carbonateHigh-boiling solvent: selected from aromatic, ketone, ester and othersolvents while confirming printabilityAluminum paste 1: heat residue 69% (Toyo Aluminum Co., Ltd., AluminumPaste TD200T, average particle size 15 μm)

TABLE 3 Example 1 2 3 4 5 6 7 Imprinting technique thermal thermalthermal thermal thermal thermal pad transfer transfer transfer transfertransfer transfer Printing technique silk silk silk silk gravure gravure— to transfer foil screen screen screen screen Ink thickness 6   6   6  6   2   2   6   per layer (μm) Structure Upper layer B C D E F G C Lowerlayer a a a a a a a Aluminum content x 2.46 4.14 6.60 8.28 4.14 5.524.14 upper layer thickness Evaluation Brilliance ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Color(visual black black black dark black black black observation) silvergray Repro- ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ duction of lower layer color Abrasion test ⊚ ⊚⊚ ⊚ ⊚ ⊚ ⊚ Impact ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ durability

TABLE 4 Comparative Example 1 2 3 4 5 6 Imprinting technique thermalthermal thermal thermal thermal thermal transfer transfer transfertransfer transfer transfer Printing technique silk silk silk silk silksilk to transfer foil screen screen screen screen screen screen Inkthickness 6   6   6   6   6   6   per layer (μm) Structure Upper layer AF G — — — Lower layer a a a a b c Aluminum content × 0.84 12.42 16.56 —— — upper layer thickness Evaluation Brilliance X ⊚ ⊚ X X Δ Color(visual black silver silver black black dark observation) gray grayReproduction of ⊚ X X ⊚ ⊚ Δ lower layer color Abrasion test ⊚ ⊚ ⊚ ⊚ ⊚ ◯Impact ⊚ ⊚ ⊚ ⊚ ◯ ◯ durability

TABLE 5 Comparative Example 7 8 9 Imprinting technique thermal thermalthermal transfer transfer transfer Printing technique to silk silk silktransfer foil screen screen screen Ink thickness 6 6 6 per layer (μm)Structure Upper layer — — — Lower layer d e f Aluminum content × — — —upper layer thickness Evaluation Brilliance ◯ ⊚ ⊚ Color (visual silversilver silver observation) gray gray Reproduction of X X X lower layercolor Abrasion test Δ Δ Δ Impact Δ Δ Δ durability

As is evident from the results shown in Tables 3 to 5, the markingmethods used in Examples, in which the content of aluminum powderrelative to the upper layer ink medium solids is related to thethickness of the upper layer so as to satisfy the specific inequality,produce printed portions having excellent brilliance and satisfactorysharpness and reproduction of black color. In contrast, the markingmethods used in Comparative Examples, in which the content of aluminumpowder relative to the upper layer ink medium solids is not adequatelyrelated to the thickness of the upper layer or in which the markinglayer is not divided into upper and lower layers, fail to providebrilliance or effectively reproduce the black color.

1. A golf ball marking method of marking the surface of a golf ball witha character, pattern or the like by a direct or indirect printingtechnique, characterized by the steps of: applying a marking layer ontothe ball surface for marking, the marking layer being of a two-layerstructure consisting of a lower layer of a composition containing acolor pigment in a lower layer ink medium and an upper layer which isformed on the lower layer from a composition containing a metal powderin an upper layer ink medium and which is transparent or translucent andhas brilliance, and adjusting the content of the metal powder and thethickness of the upper layer such that the relation of the content (wt%) of the metal powder relative to the solids of the upper layer inkmedium to the thickness (μm) of the upper layer may satisfy theinequality: 1≦[metal powder content (wt %)]×[upper layer thickness(μm)]≦10.
 2. The golf ball marking method of claim 1, wherein thecharacter, pattern or the like is marked by a pad printing technique. 3.The golf ball marking method of claim 1, wherein the character, patternor the like is marked by thermal transfer using a transfer member. 4.The golf ball marking method of claim 3, wherein a mode of printing thecharacter, pattern or the like on the transfer member is silk screenprinting.
 5. The golf ball marking method of claim 4, wherein the silkscreen printing uses a screen having a ruling of 200 to 300 lines. 6.The golf ball marking method of claim 1, wherein the metal powder has anaverage particle size of up to 20 μm.
 7. The golf ball marking method ofclaim 1, wherein the metal powder is an aluminum powder.
 8. The golfball marking method of claim 3, wherein a mode of printing thecharacter, pattern or the like on the transfer member is gravureprinting.
 9. A golf ball characterized in that a marking layer is formedon the golf ball surface by the method of claim 1.